The present invention relates to a device for changing the flow of an operating medium in a heat pump air conditioning system, designed to change the mode of operation. More particularly, the present invention is directed to a novel flow directional control device which includes an improved drive mechanism for a valve body, which utilizes differential pressure resulting from the difference between effective pressure bearing areas, which improves sealing integrity of the entire casing, and which includes a seal configured to follow movement of the valve body so as to more effectively seal the casing against leakage of the operating medium.
A typical air conditioning system includes indoor and outdoor heat exchangers between which an operating medium (as a gas under low or high pressure flowing through the indoor heat exchanger, a compressor and the outdoor heat exchanger and as a liquid flowing through the outdoor heat exchanger, a capillary tube and the indoor heat exchanger) is circulated to discharge indoor heat to the outside of a room or introduce outdoor heat into the inside of the room so as to adjust the temperature in the room. The operating medium is reversed to provide cooling or heating mode of operation. A reversing valve or four-way valve is required to reverse the flow of the operating medium since practically, the compressor is not effective.
A conventional reversing valve includes a valve body slidably moved to provide cooling or heating mode of operation, as disclosed in Japanese laid-open patent publication No. 61-6468. It is, however, difficult to maintain such a sliding valve body in close contact with a sliding surface. Also, the valve body can not smoothly be moved on the sliding surface as resistance to sliding movement increases. This makes it difficult to change the mode of operation. Undesirable friction is also developed when the sliding valve body is repeatedly slid under high pressure. Such friction deteriorates sealability. The sliding valve body requires the use of selected materials and complicated machining techniques since there is a limitation on its structure. Furthermore, the prior art valve is complicated in structure, requires a larger number of parts and assembly steps and is costly.
The inventor addresses the problems of the prior art four-way valve and has made extensive searches in an effort to provide a novel four-way valve with enhanced sealing integrity.
It is a first object of the present invention to provide a novel drive mechanism for a valve body, designed to overcome various problems associated with the prior art sliding four-way valve.
It is a second object of the present invention to provide means for making a sealing element function in an efficient manner.
It is a third object of the present invention to improve sealing integrity of a casing wherein a through hole is formed to receive a drive member, typically located outside of the casing within which a valve body is contained.
It is a fourth object of the present invention to avoid a loss of sealing integrity which may occur when a clearance is formed between a first port and a first selectively positionable opening as a result of movement of a valve body.
The prevent invention is intended to achieve the foregoing objects and provides a novel device for changing the flow of an operating medium, which includes a drive mechanism for a rotary type valve body, which utilizes differential pressure resulting from the difference between effective pressure bearing areas, which seals the entire casing against leakage, and which includes a sealing element configured to follow movement of the valve body.